The Noble Qur'an clearly states...

The Noble Qur'an clearly states: “The one who continues to sin until he witnesses death and then begins to experience regret, saying, `Now I repent' the repentance of such a one will not be accepted.” (4:18) Once someone said in the presence of the Commander of the Faithful, upon whom be peace, in an offhand and careless fashion, “I seek the forgiveness of God.” The Imam said to him: “May your mother weep for you! Do you know what it is to seek the forgiveness of God?

Seeking forgiveness of God is the station of those of high rank. It appears to be but a word, but it includes six aspects.

The first is regret for what has been done; the second is firm resolve to abandon sinning in future; the third is restoring to others whatever rights of theirs you may have usurped, in such a way that when you meet your Creator they will have no claim in you; the fourth is that you perform whatever obligatory acts of worship you may have neglected; the fifth is that you cleanse with the tears of regret the illicit flesh that grew on your body while you were sinning; and the sixth is that just as you tasted the pleasure of sin and disobedience, you now taste the hardship and rigor of worship and obedience.

Only when you have completed all of these six may you say, `I seek forgiveness of God.'“ ( Nahj al-Balagha, ed. Subhi Salih, p. 549) The Qur'an says concerning the repentance of the usurers: “If you do not abandon usury, be aware that you are engaged in war against God and His Messenger. But if you truly regret your practice and repent of it, then the original sum shall be yours; no wrong shall be done to you, nor will you have wronged others.

If one of your debtors is indigent, grant him a respite until he is able to pay; and if you forgive him his debt by way of charity, this will be better for you, if you are aware of your own true interest.” (2:279-280) The Qur'an pronounces the repentance of the usurer to be a true repentance only if he renounces the interest that is due him and simply reclaims the original sum; in such a case, neither will he have wronged anyone nor will he have been wronged himself.

The Qur'an then adds that it is better for the lender to give a respite to the borrower, enabling him to obtain the money needed for repaying the debt. If the lender forgives the debt, it will be still better, the reason for this being that it is usually dire need that forces people into debt.